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Separate cortical stages in amodal completion revealed by functional magnetic resonance adaptation : research article
Background Objects in our environment are often partly occluded, yet we effortlessly perceive them as whole and complete. This phenomenon is called visual amodal completion. Psychophysical investigations suggest that the process of completion starts from a representation of the (visible) physical features of the stimulus and ends with a completed representation of the stimulus. The goal of our study was to investigate both stages of the completion process by localizing both brain regions involved in processing the physical features of the stimulus as well as brain regions representing the completed stimulus. Results Using fMRI adaptation we reveal clearly distinct regions in the visual cortex of humans involved in processing of amodal completion: early visual cortex - presumably V1 - processes the local contour information of the stimulus whereas regions in the inferior temporal cortex represent the completed shape. Furthermore, our data suggest that at the level of inferior temporal cortex information regarding the original local contour information is not preserved but replaced by the representation of the amodally completed percept. Conclusion These findings provide neuroimaging evidence for a multiple step theory of amodal completion and further insights into the neuronal correlates of visual perception
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Customized design of hearing aids using statistical shape learning
3D shape modeling is a crucial component of rapid prototyping systems
that customize shapes of implants and prosthetic devices to a patient’s
anatomy. In this paper, we present a solution to the problem of customized 3D
shape modeling using a statistical shape analysis framework. We design a novel
method to learn the relationship between two classes of shapes, which are related
by certain operations or transformation. The two associated shape classes are
represented in a lower dimensional manifold, and the reduced set of parameters
obtained in this subspace is utilized in an estimation, which is exemplified by a
multivariate regression in this paper.We demonstrate our method with a felicitous
application to estimation of customized hearing aid devices
Introduction to fMRI: experimental design and data analysis
This provides an introduction to functional MRI, experimental design and data analysis procedures using statistical parametric mapping approach
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